7 Reasons To Lift Heavier Weights

While cardio is essential for heart health and tiny weights may help you tone, there are lots of serious, science-backed reasons to add heavy weights to your regimen. (And no, you won't end up looking like a body builder. That's actually a full-time job.)

"Lifting heavy weights—about 8-15 pounds for women is fine and up to 25 is ideal—is the most efficient and effective way to build muscle mass," says Joey Gonzalez, owner of Barry's Bootcamp in New York.

"Developing muscle is crucial to lowering body fat, and to improving your fitness and health levels overall," he says. And lots of studies would agree with him. Here are seven research-tested reasons women should lift heavy...

Heavy weights are crucial for weight loss. "Generally speaking, for each pound of muscle you gain, you burn 35 to 50 more calories each day," says Gonzalez. Studies have shown that adding weight training to your cardio routine increases after-burn, so that once you've showered and settled into your desk chair, your body will continue to burn calories.

In one study published in Medicine & Science in Sports & Exercise, women who lifted more weight for fewer reps burned nearly twice as many calories during the two hours after their workout than when they did more reps with a lighter weight.

And research has also shown that strength training burns body fat more exclusively, while cardio alone can cause both fat and muscle loss.

Healthy bones need heavy weights. Weights do your body good the way milk, most likely, does not. A regular weight-training routine has been shown to significantly increase bone density, which can help protect you from osteoporosis down the road. "Lifting heavy weights over time not only maintains bone mass, but it can even increase bone mineral density, even in the post-menopausal women," says Gonzalez. "Consistency is key."